‘Tour de force’ experiment probes quantum tunnelling in action Probing photons inside a barrier also challenges a long-standing interpretation of quantum physics.

When presented with a stimulus, or cue, that has been paired with a reward, some animal lean to interact with the cue.

Nicholas Spangler is a general assignment reporter and has worked at Newsday since 2010.

Explore news and insights on climate change, environment policies, global warming and sustainable practices with The New York Times Climate and Environment section.

Yahoo Sports is on the road this summer hitting camps across the country, and we're rounding up the news, updates, position battles and more you need to know.